Recovery of values from rock asphalt and like material



Nov. 29, 1949 J w COAST 2,489,701

RECOVERY OF VALUES FROM ROCK Q ASPHALT AND LIKE MATERIAL 2 Sheets-Sheet 1 Filed July 20, 1946 INVENTOR John If. fiaas/ BY Mg m ATTORNEY Nov. 29, 1949 J. w coAsT 2,489,701

RECOVERY OF VALUES FROM ROCK ASPHALT AND LIKE MATERIAL 2 Sheets-Sheet 2 Filed July 20, 1946 INVENTOR Il /tn [ba sf BY I ATTORNEY Patented Nov. 29, 1949 2.48m. RECOVERY OF' VALUES FROM' ROCK ASPHALT AND LIKE MATERIAL J ohn- W. Coast, Dallas, Tex., assignor of oneelialf to Clarence H. Dragert, Dallas, Tog.

' Application July 20, 194.6, Serial No. 685,067

In Cuba August-4, 19415 2 Claims. (01. 196-150).

The. present invention relates to a p ocess for the.- treatment of rock asphalt, Qi'1':. jh 9S- an like material, which contain both oil-soluble hydrocarbon and oil-insoluble. inorg nic po i n t recover valuable petroleum products therefrom,

More particularly the. present invention relates to: a process as above. set forth, wherein provision is made. for producing cracked petroleum zvroducts, including high octane gasoline, by a cracking operation taking. place in the presence f. clay type material, which is, derived from and is a. part of the original raw material on which the process is intended: to operate.

While the present process is considered to be. applicable to many types of rock asphalt, oil shales; oil sands and other similar raw materials found in various parts of the. world, it is particularly adapted for the treatment of this type. 015 material which is found in Cuba, wherein the material consists of somewhat over 50% oil-soluble hydrocarbon or bituminous material and the remainder a fine volcanic ash, which has a composition similar in many respects to certain clays.

The problem of treating such material for the recovery ofvalues therefrom involves .two basic elements, first the separation of the inorganic materials from the organic hydrocarbon materi als, and second the separation of the hydrocarbon materials mto selected individually usable fractions or portions, which may be used as such for various known purposes. Various solutions of this problem are. disclosed in my copending application in the United States, Serial No; 685,- 066, 20,1946, this application having to do particularly with a separation effected between a: solution in oilof the oil-soluble material from the major portion of the inorganic material by a process based upon specific gravity differonce. I have also disc-losedin Cuban application Ser., No; 97,802, filed August 4,1945, a process relating particularly to the effecting of this separation by volatilizing substantially all the volatile portions of the oil-soluble material of the raw material and'the solvent leaving as a residue the inorganic materials and some relatively non-volatile organic materials, portions of which latter may be recovered in one form or another. The present invention may employ either or both or these means of separation, but emphasizes particularly the cracking of products resulting from straight run operations to produce cracked pee troleum products including, for example, high-test or high octane gasoline. V

It has previo sly been proposed to use a so called fluid catalyst method of obtaining high ne a o ine y wre k n tio in he presence of a relatively large quantity. of clay typematerial such as qr similar to fullers. earth, Hera o er! the c ay ma er a h ch i sed. possibly as: a catalyst, but in any event to assist. the. cracking operations in the making of high octa e gasoline, most all b ob ained f eI rnal sour e and any such me lw i his; used u o os 1 th? process m st be. rep et s u c s.- pres nt in en on i to 'r on s milar in som ic he known ui at e sq-c ll at .wlw y It m he r s l 7 i. als lie tothep ce s so ea in the normalcneratl loi th proces her ill. always be obtaln don th final cts. or t e p es amou t o h c a type m net. ieh m n ic i conti us eing snpplied to the process as one th rad ent of therew m r In t the present process will be not only Sub: stantially as efllcient as, the process heretofore known-irom the point of view of the resultant hydrocarbon products produced thereby, but also be. much cheaper as it is unnecessary to 1001; elsewhere 0 F irrem u e in efiecting the cracking operation.

Eurther detailed .ob' ts of the present invenon .of process steps for material used in the sh s operat n and re-cycl n this reac vated material to a selected extent; provisions to owerin t ee throu h u e p ess y theuseoi suitable heat interchangers; and other E W 935 tqw ethodq process wh ave now become accopted practices throughout the oil refining industry, Other; and more detailed objects of the preseninvention will become apparentir-om the. follo g specification and appended claims, when taken in connection with t e accomp ny ng dr ngs i Whichr I Figure 1 is a diagrammatic view illustrating one form. of equipment by which the process of this invention may ,be. oarriedout; and

Fig, 2 is a similar view ill lstratinganother form of such equipment for thecarr-ylng out of a slightly modified process-in accordancewith this invention.

Inasmuch as the .-tw o- ;forms shown in Figs. ;1 and .2 of theaccompanying drawings have many features of process andrnany structural elements n o m n such common st uc e ements wi h siren h same: reierence c aracters and 3 the description thereof will not be repeated in detail.

The first operation in treating material of the kind above set forth is to dissolve the oil-soluble portion thereof in a solvent, which is obtained from a subsequent step of the process, and is largely material of the type known in the art as gas oil. This solution is preferably facilitated by first comminuting the raw material or may take place either without such comminuation or simultaneously therewith as desired. In accordance with the present teachings, it is assumed that the material supplied to the apparatus hereinafter generally described is first comminuted, so that a major portion is of a size range of 30 to 40 mesh. This material is supplied to a hopper i and passes thence to a standpipe 2 under control of a suitable valve mechanism 3, such as a proportioning valve which controls and regulates the rate of feed of the material to the standpipe 2. As shown there is introduced into the upper portion of the standpipe 2 a supply of solvent which passes thereto through a line 4 under control of a valve 5 in this line. The material thus partially mixed fiows, preferably by gravity, to a mixing tank 6 having associated therewith means for thoroughly mixing the materials and thus facilitating the solution of the oil-soluble portion of the raw material. In the present instance this mixing means is shown as a stirrer l suitably mounted in the tank 6 for rotation and arranged to be driven by any desired means (not shown) associated with a gear 8 secured to, the upper end of the stirrer 7. It is preferred that the mixing and solution take place with the material hot, so as to facilitate solution and also, to keep the viscosity of the solution down to a desired point. For this purpose the temperature of the incoming solvent and possibly also of the incoming raw material is such that the solution will take place with the mixed materials in atemperature range of about 250 to about 450 F. and with a preferred temperature of about 350 F.

" Material passes from the mixing tank through a line 9 to a vapor separator [8 wherein any constituents of the material which will vaporize at the temperature existing within the separator scribed. Thus far the description applies to both forms of the invention shown in Figs. 1 and 2 of the drawings.

Referring now to Fig. 1 of the accompanying drawings, the liquid from the vapor separator l0 passes through a line I2 from the lower portion thereof and under control of a valve l3 in this line to a separation equipment I4, wherein a separation is effected between liquid and solid materials to a very large extent. In the usual case this separation will be sufficiently complete that about 90% to 100% of the solid materials :along with some solvent liquid will be separated from the remaining primarily liquid material.

This separation equipment may take various forms as set forth more particularly in my aforesaid copending application in the United States, Serial No. 685,066, filed July 20, 1946. It may comprise continuous or intermittent filtering equipment or it may involve a separation based upon specific gravity difference and including any one or more of the following types of equipment: (a) settling tanks; (b) clarifiers or classi- -fiers such as those made by the Dorr Co.; or (c) intermittent or continuous centrifugal separation equipment. While all these types of equipment may be equally effective from the point of view of separation between the two types of materials as aforesaid, it is presently preferred to use continuous centrifugal separation wherein the separation is effected based upon specific gravity difference. Any of the other named means for separation is, however, to be considered within the purview of this invention and within the scope of the appended claims, which are not otherwise specifically restricted to some one named type of separation at this point.

The liquid material resulting from this separation may pass from the apparatus I through a line i5 to a pipe still heater l6 wherein it may be heated up to a relatively high temperature sufiicient to vaporize most, if not all, of the volatile constituents thereof. This temperature is contemplated to be in the range of about 750 to 950 F. and preferably about 850 F. It will be understood that the heat may be supplied to the pipe still heater in any usual manner as by the combustion in a suitable combustion space of any available fuel, a stack I! for the products of combustion being indicated on the accompanying drawing. Material passes from the pipe still heater I6 through a line iii to a vapor separator [9, wherein volatile constituents are separated from the non-volatile residue including substantially all the inorganic materials, which have not previously been separated from this portion of the material flowing out of the equipment or apparatus I4. Such non-volatile materials may pass from the lower portion of the vapor separator [9 through a line 23 under control of a suitable valve mechanism 2! for such use as they may be put. No further details of this use or treatment of this material will be included in the present application as they form per se no necessary part of this invention.

Vapor passes from the upper end portion of the separator l9 through a line 22, in which is preferably interposed an apparatus 23 for removing remaining solid particles therefrom, this apparatus preferably being of well known electrical type such as a Cottrell separator. Line 22 passes to a heat interchanger 2a in which the temperature of the Vapor is reduced to some extent and the heat thus obtained utilized for heating other material not specifically disclosed herein, but which may pass to and from the interchanger through lines indicated at 25 and 26. The somewhat cooled vapors pass thence through a line 2'! under control of a valve 28 to a fractionating tower 29, which may be of the well known bubble type.

In the fractionating tower the usual and well known fractional condensation takes place, resulting in a desired number of different fractions having different specific gravities. Only a few fractions of these are indicated on the accompanying drawings. As shown there is a line 30 from the top of this tower for non-condensible gases and vapors, which line joins the line H, so that vapor from both lines pass to a suitable point (not shown). Straight run gasoline may also be drawn from the fractionating tower 29. As shown, however, there is a line 3| from which a fraction, preferably having the characteristics of gas oil is drawn. This material serves, accordance with the present invention, for two essential purposes, first as a source of solvent for supply to the dissolving step of the process through the line 4, and second, as a source of g cracking stock or material to be cracked in ace cordance with the principles of this invention as: hereinafter to be set forth indetail.

In order that the material flowing through the line 31 under control of a valve 32 in this line may be further heated, as heat is needed irrespective of which oithe uses above set. forth the material is to be put, it is passed to a heating and storage tank 33 in which are heating coils as shown and some of the heavier fractions with drawn from the tower 29 pass through the lines 34 and 35', thence through these heating coils en route to their delivery or collection points, as these heavier fractions come out: of the tower at substantially higher temperatures than that. of the material passing through the line at. A line 36 having interposed therein a pump mechanism 31- serves for the flow of this material fromtheupper portion of the tank 33 to the line 4 and also to the cracking portion of the process hereinafterto be described. The particular descrip tionthus far given of the Fig. 1 form of the invention corresponds substantially to a similar partof the disclosure of my copending United States application Serial No; 685,066, filed July 20, 13946 and may be amplified by various. of the details more specifically given in that application.

In the form of the invention shown in Fig. 2-, the liquid material from the separator Ill passes from the lower portion thereof through aline 38 control of a valve-39, direct to the pipe still heater #6, through which all the materials (except as hereinafter set forth), including the inorganic material in suspension, pass and are heated; This material passes thence through the line l8 to the vapor separator H] as inthe form previouslydescribed. Here, however, it may be desired that some of'thematerial from the vapor separator t by-passthe pipe stillheater "5. For this purpose a bypass line 40' is provided having a valve 4l=therein and extending between the lines- 38: and t8 as shown. Furthermore, if it is desired to dilute the material passing through thepipe still heater IS inthis form of the invention, a second by-pass 42 is provided between the line 4 and theline 38*, a valve 43 being provided in this line for controllingthe' flow thcrethrough. In-th-is way the degree of-dilution of the material flowing through the pipe-still heater I'G- may be controlled and the temperature of the materials flowing through the line I 8 to the vapor separator I 9 may also be controlled by controlling; the amount of material passingthrough the line to.

In this form of the invention, the line is shown coming; from a source (not shown), which may-be a reservoir for-permanent gases of, a reducing character, the line 26 being shownjoini-ng the line 38 intermcdiate the valve 39-and the pipe still heaterl6, so as tointroduce these gases into the-flowof'material'passi-ng through the pipe still heater. This is often useful in treatment of materials containing substantial amounts'of sulfur as the reducing gases react with such sulfur to form hydrogen sulfide, which may be recovered from the gases passing ou't'ofthe top of the tower 29' through the line by scrubbing these gases with an absorbent liquid.

In this form of the invention the line 30 joins the-line I l and thence is shown passing to a vapor separator 44 under control of a valve 45. Interposedin this line prior to the valve 45 is a suitable cooler 45, which serves to reduce the temperature of the vapors and gases passing therethrough up to a point such as permit the condensation of anynormal ly liquid materials. These materials are. separated from. the p rmanent gases in the vapor separator 4.4 and from the lower end.- thereof through a 4.1:, which joins the. line 3%? previously described The. line 41 has a valve 48 therein controlling the flow or this material to join the line. 3E. If desired, however, a part or all of this material may pass out to a desired collection point through. a branch line. 49. under control of a valve 50 therein. Permanent gases pass from; the vapor separator 44 through a line 5-1 to a suitable gas collection pointv and preferably pass through one or more scrubbing towers (not shown) on route thereto, these gases being used for any desired purpose and being preferably in. part. returned through. the line 25 abovedescribed. There. is also shown a valve 52 in the line s between the; pump mechanism. 3-land the branch line. 42 and beyond the point where a line passes to the cracking portion. of the system hereinafter to be described, Furthermore, it may be desired to. withdraw from the. system a part of the gas oil withdrawn from the tower 29 through the line 3 1-. For this purpose. a branch. line; 533 is shown having a valve 54 therein.

The subject matter described hereinabouc. and which is shown: in Fig, 2. of: the accompanying drawings is describedingreater detail in. my co.- pend-ing Cubanapplicatiom Serial. No. 97 ,082, filed Aug; 4;, 1945.

Considering thecracking: portion of the process per se, it

be noted that the. forms shown in: both Figs. 1: and 25 are substantially identical as to this. phase of? the operation, The various elements will? therefore be referred to by the same reference characters.

In both figures of thedraw-ings, the cracking stock is withdrawn from line. 4 on the: output side of' the-pump: 31 and passes through aline- 55 under control; ot 'a valwee 56 there-in to and through a heating furnace 51 which may: be essentially similar to the pipe'stih-heater- I E above described. This oilor cracking stock may pass thence through aline 58 to a cracking chamber 59". It isalsodesired to suppl'y'tothe cracking chamber a clay type material toact -in someway, the details of which are not clearly understood, but which may resemble catalysis. In accordance with the present inventionthe sourceof this clay type material is' the: inorganic material entering the processw-ith and as apart of the raw material supplied theretoas aforesaid. This inorganic material' passes, in the form of the inventionshown in Fig; 1; through a line 60 from the specificgravity separation equipment l4 directly to the crackingchamber 59 under control of a valve 61. While this-material has some organic materials therewith; this will not interfere with the cracking operation to any substantial extent as the clay material is-tobe-mixed with an organic oil; charge of the-cracking chamber.

In the Fig. 2 form of the invention the inorganic material'is separated from the organic material in. the. separator l9, and passes. from the lower portionthereof, through a line 62 under con,- trol of a suitablevalve therein. as shown to the cracking chamber. 59.- Here again there will be some. organic. material; mixed with this. clay or inorganic material, although.- arelatively smaller amount than in the; Fig; 1. form and of less volatile character; This: d-iffierence. is substantially immaterial from the point of view of the operations taking place in the cracking chamber and subsequent thereto as hereinafter to be described.

" it is necessary that the materials during their passage through the crackingchamber be brought up to a relatively high temperature, which is contemplated to be within outside limits of about 850 to about 1400 F. and preferably within :the somewhat narrower range of about 1000 to about 1100 F. For certain materials, for example, this range may be even more specific and is contemplated to be in the order of magnitude of about 1050 F. This heating may :be accomplished in several ways. It is contemplated for example that the heating may be effected internally by supplying to the ,cracking chamber a highly heated fluid material, such as products of com bustion as hereinafter specifically to be described. It is further contemplated thatthe heating of the materials in the cracking chamber may be external, so that the chamber itself acts as a It is also contemplated that any of the clay materials, that is any desired :part or all of them, may be heated to asufiiciently high temperature so that the heat contained therein as introduced into the cracking chamber will be suficient to raise the entire .contents of this chamber to the desired temperature range as aforesaid. Any of these processes or any combination thereof is to be considered within the purview of this invention and. within the intended scope of the appended claims, except as such claims ma be further specifically limited.

As shown, there is provided a generator 63 for products of combustion, to which air and gas are respectively supplied through lines 64 and 65 having respectively interposed therein control valves t and $1., Products of combustion from lthe generator 63 may pass through a line 68 under control of a suitable valve 69 therein to the cracking chamber 59 to mix with the materials therein and establish and maintain the desired temperature conditions in this chamber.

Material passes from the right hand end as seen in the drawings of the cracking chamber 59 to a reaction chamber 70 which also serves as a vapor separator, the vapor passing from the upper end of this chamber and solid materials including the inorganic clay material and any non-volatile materials remaining therewith pass out through the lower end of this chamber.

Tracing first the course of the vapor from the chamber Hi, this vapor may pass through a line i H from the upper portion thereof, through a device i2, for separating solid particles from the vapor and which may be essentially similar to the device 23 above described. Thence the vapor passes to and through a heat interchanger 73,

per end of the tower is may pass through a line 'i'l, thence through a cooler E8 to a vapor separator l8, a valve 86 being interposed in the line H for suitable control purposes. The products of combustion and other non-condensible gases will pass from :the vapor separator 79 through a line 85 to any other suitable mechanism by which any values remaining in these gases may be recovered and the remaining gases discharged to the atmosphere through a stack. Suitable valves, not numbered, may be interposed in the lines 8| and 82 to maintain a desired pressure in the vaporseparator 19 and some previous parts of the system. Liquid materials condensed in the cooler 18 and separated from the'gases in the separator 19 may pass from the lower end thereof through a line 82 (Fig. 2) to a suitable point of use or through a line 83 (Fig. 1) to mix with cracked gasoline passing from the upper portion of the tower 75 through a line 84, suitable valves '85 and 86 being interposed in this line as shown. Either of these arrangements may be used as desired.

Another material which may be withdrawn from the tower i6 is a material in the gas oil range of specific gravities, that is one having the essential characteristics of :the gas oil above described or the cracking stock, which is used to be supplied to the cracking chamber 59 as aforesaid. This material maybe withdrawn from the tower 16 through a line 81 and a selected part thereof may pass to the line under control of a valve 88 in the line 87 for re-cycling as may be desired. The balance of it may pass through a branch line 89 under control of a valve 98 therein to a suitable collection point. It will be understood that -re-cycling of the gas oil from the tower 75 may be used or not as desired or a selected proportion of this material may be re-cycled, all within the purview of this invention.

In Fig. 1, one of the heavier fractions, for example fuel oil, may be withdrawn from a lower portion of the tower 16 through a line 9! under control of a valve 92. In both figures a line 93 is shown from the bottom of the tower 76 for heavy tarry material, which may flow to a desired collection point under control of a valve 94 in this line.

The residue material including substantially all the inorganic material and any non-volatile organic materials remaining therewith may pass from the bottom of the reaction chamber through a suitable valve mechanism 95 to a combustion chamber diagrammatically illustrated at 96, the valve 95 being so designed as to feed this solid material to thte furnace at a predetermined desired rate and to prevent to a substantial extent at least, flow of products of combustion from the combustion chamber into the reaction chamber 76. In the combustion chamber 96 a suitable amount of air may be supplied in any manner not particularly shown to burn out from the inorganic materials any remaining organic and hence combustible material remaining therewith and thus to efiect a re-activation of the inorganic or clay type materials. If desired, or found necessary, a suitable amount of fluid fuel may be introduced into the combustion chamber 86 to insure the operations aforesaid and for supplying a desired amount of products of combustion to the heater 5?. Products of combustion from the combustion chamber 9-6 may pass through a suitable conduit 9'! to the pipe stillheater or furnace 51, so as to heat the oil or cracking stock passing therethrough between the pipes 55 and these products of combustion exhausting through a suitable stack 98.

The remaining inorganic materials, which have been reactiviated as aforesaid and which now contain substantially no organic materials, may pass from the combustion chamber 95 through a suitable means here indicated by the line s9 and a part of them be supp to a storage chamber ltd for this material under control of valve mechanism generally indicated at ltl. This material is preferably kept hot as far as possible and may pass thence through suitable means indicated by the line I02 under control of a valve mechanism I03 to the lines 60 or 62 en route to the cracking chamber 5.9..v

It is contemplated that in accordance with the best practice now. in use in the "fluid cracking of petroleum products above referred to, a substantial amount .of .clay type material will be ire-cycled in this way, so that there will be a predetermined desired ratio of clay to organic material in the cracking. chamber 59. The apparatus herein described is susceptible of operation for establishing any desired predetermined ratio of re-cycled inorganic material, so as to establish a desired ratio between organic and inorganic materials in the cracking chamber. The present invention is not specifically limited to any particularly ratio, but rather to the process generally by which a desired ratio of re-cycled, re-activated clay material may be established and maintained.

Once the desired conditions have been established as aforesaid, it will, of course, be necessary to withdraw from the process substantially the amount of clay or inorganic materials which are fed into it with the original raw materials in any given unit of time. For this purpose the materials from the line 99 are preferably divided and a portion passed through a heat interchanger I04 under control of a valve mechanism I 05. In this heat interchanger a maximum amount of the heat from the hot clay type material to be removed from the process is recovered for use for any desired purpose, such 'as in pre-heating the oil charge for the cracking chamber passing through the line 55. For this purpose there is shown branch lines I06 and H11 leading from the line 55 to the heat interchanger and thence back to the line 55 respectively, a valve I08 being interposed as shown in the line I and a suitable valve I09 being interposed in the line 55 between its connections with the lines I06 and I01, so as to control the proportion of the material passing through the line 55 which will be diverted to pass through the heat interchanger I04. Within the heat interchanger I04 there is shown a helical screw conveyor I I0, which may serve to cause the movement of the clay material therethrough in a known manner, this material passing therefrom through a line pipe or duct III to any suitable disposal point. This clay may be disposed of by dumping it at any available point or ma be used for any purpose for which it is suitable.

While there is shown and described herein but two embodiments of the invention, which are similar to one another in many respects, but show the use of certain variants in others, it is contemplated that other variations will occur to those skilled in the art. I do not wish to be limited, therefore, except by the scope of the appended claims, which are to be construed validly as broadly as the state of the prior art permits.

What is claimed is:

1. The process of treating rock asphalt, oil shales and like material, containing both 011- soluble hydrocarbon and oil-insoluble inorganic portions, to recover valuable petroleum products therefrom, which comprises the steps of dissolving the oil-soluble portion of such material in asolvent oil, which is produced at a subsequent step in the process, separating to a substantial extent the solution of the oil-soluble portion from the remaining material, processing the separated oilsoluble portion and the solvent oil to recover valuable petroleum products therefrom including a sup-ply of said sol-vent oil and a quantity of a cracking stock, introducing said cracking stock and said remaining material into a cracking chamber, separately generating hot products of combustion and passing them into said cracking chamber to heat the materials passing therethrough to a. temperature .in the range of about 850 to about 1400* F., passing said materials from saidcracking chamber to: a vapor separator and therein vaporizing volatile portions thereof, separating the resultant vapor from the remaining non-volatile materials, processing such vapor to produce valuable cracked petroleum products therefrom including cracked high octane gasoline and a quantity of material similar in its characteristics to said cracking stock, passing said remaining non-volatile material into a combustion chamber and therein burning substantially all the combustible material therefrom, removing the non-combustible material from said combustion chamber, cooling a selected part of said non-combustible material and utilizing heat obtained therefrom for pro-heating said cracking stock en route to said cracking chamber, recycling the remaining part of said non-combustible material through the cracking process by introducing it into said cracking chamber so as to establish and maintain therein a predetermined ratio between inorganic and organic materials, utilizing heat derived from the combustion in said combustion chamber for further pre-heating said cracking stock en route to said cracking chamber, and re-cycling a selected amount of said material similar in its characteristics to said cracking stock by reintroducing such material along with said cracking stock into said cracking chamber so as to establish a predetermined ratio between this re-cycled material and said cracking stock in the materials introduced as aforesaid to said cracking chamber.

2. The process of treating rock asphalt and 1ike material, containing both oil-soluble hydrocarbon and oil-insoluble inorganic portions, to recover valuable hydrocarbon products there-from, which comprises the steps of dissolving the oil-soluble portion of such material in a solvent oil, separating to a substantial extent the solution of the oil-soluble portion from the remaining material, vaporizing the volatile portion of said solution of the oil-soluble portion and separating the resultant vapor by fractional condensation into a plurality of straight run fractions, one of which is suitable as a cracking stock, and one of which is suitable for use as said solvent oil, introducing said cracking stock and said remaining material into a cracking zone, heating the materials thus introduced into the cracking zone to a temperature in the range of about 850 F. to about 1400 F. while they are in the cracking zone, separating the eflluent from the cracking zone into a vapor portion and a spent inorganic residue separating said vapor portion into a plurality of cracked hydrocarbon fractions, subjecting said spent inorganic residue to the action of an oxygencontaining gas at a temperature sufficient to burn out all combustible material therefrom to generate hot products of combustion and to produce a hot inorganic material suitable for use as a cracking catalyst, supplying heat from said hot products of combustion thus generated to said cracking zone, and reintroducing into said cracking zone a selected part of said hot inorganic material cracking catalyst so as to effect some catalytic cracking in said cracking zone and to estab- 11 12 lish and maintain in said cracking zone a precle- UNITED STATES PATENTS termined ratio of inorganic to organic materials Number Name Date independently of the ratio of inorganic to organic 1 327 572 Ryan Jan 6 1920 materials in the original material supplied to the 1357f278 D ay 1920 5 11461758 Day Sept. 11, 1923 JOHN COAST 1,475,901 Thompson Nov. 27, 1923 1,706,468 Struben -1, Mar. 26, 1929 REFERENCES CITED 1,778,515 Hampton Oct. 14, 1930 The following references are of record in the 2,339,932 Kuhl Jan. 25, 1944 file of this patent: 2,406,810 Day Sept. 3, 1946 

